US1029311A

US1029311A - Governing mechanism for mixed-pressure turbines.

Info

Publication number: US1029311A
Application number: US66813011A
Authority: US
Inventors: Wilhelm Pape
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1911-12-27
Filing date: 1911-12-27
Publication date: 1912-06-11
Anticipated expiration: 1929-06-11

Description

W. PAPE.

GOVERNING MECHANISM FOR- MIXED PRESSURE TURBINES. APPLICATION FILED 13110.27, 1911' Patented June 11, 1912.

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,nventor; Wilhelm Pape, b3

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w. PAPB. I GOVERNING MECHANISM FOR MIXED PRESSURE TURBINES.

APPLICATION FILED D110. 27, 1911.

Patented June 11, 1912.

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Invenbor; WHh'elm Dape.

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COMPANY, A CORPORATION OF NEW YORK.

GOVERNING- INIECHANISM FOR MIXED-PRESSURE TURBINES.

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Specification of Letters Patent.

Patented June 11, 1912.

Application filed December 27, 1911. Serial No. 668,130.

- To all whom it may concern:

Be it known that I, WILHELM Parr, a subjectof the King of Prussia, residing at (Jlaarlottenburg, Germany, have invented certain new and useful Improvements in Governing Mechanism for Mixed-Pressure Turbines, of which the following is a specification.

The present invention relates to govern ing mechanism for turbines which are normally operated by low pressure steam such as the exhaust from a reciprocating engine and at other times by a mixture of high pressure and low pressure steam, and when the supply of low pressure steam fails by high pressure steam only. Such a turbine ls-cominonly known as a mixed pressure turbine. Between the engine and the turbine 'is located an accumulator that serves to equalize the pressure of the supply of steam entering the turbine.

The object of my invention is to improve the construction and operation of governing mechanisms for said mixed pressure turbines.

For consideration of what I believe to be novel and my invention, attention is called to the accompanying description and claims ap ended thereto.

overning mechanism for mixeu pressure turbines has heretofore been provided in which the'speed governor driven by the turbine acts simultaneously upon the low and high pressure valves regulating the admission of steam to the turbine. Mechanism of this kind has also been provided wherein the movement of the low pressure valve is utilized to return the pilot valve to the motor actuating the high pressure valve to its initial or central position so that the high pressure valve will be held in its initial position as long as the low pressure valve is capable of movement. This governing mechanism has the disadvantage, however, that the accumulator, as soon as the high pressure valve is open, is placed in unrestrict ed communication with the turbine. This results in' establishing the same vacuum in the accuniula 1' that exists in advance of the low pressure part of the turbine. A further disadvantage resides in the fact that the,

high pressure valve does not operate until the low pressure valve is entirely open so that asthe supply of low pressure steam decreases below a predetermined value a certain decrease in speed of the turbine is necessary in order that the speed governor may move the low pressure valve to its final position. A further decrease in speed is then necessary in order that the high pressure valve may make the necessary stroke or movement. Under these conditions it will be seen that a considerable re duction in speed is necessary in order to pass from low pressure to high pressure op eration. If a three-phase electrlc generator is driven by the mixed pressure turbine which must work in parallel with. other generators then a decrease in the speed of the turbine such as is necessary cannot be obtained. On the contrary the load on the generator will decrease to correspond with the decreased supply of low pressure steam and the load will be taken by the other generator connected in parallel therewith. In this case the speed of the turbine will remain constant and therefore the speed ,governor will be incapable of-opening the high pressure valve.

With my'improved construction I am able to avoid all of these disadvantages. I accomplish this by controlling the low and high pressure valves by a speed governorthat is responsive to changes in speed of the turblne and also by means of a regulator or device that is responsive to changes vin pressure in the accumulator from which the turbine receives its steam. The parts are so arranged that the same means, such as a lever for example which maintains the pilot valve of the motor of the high pressure valve in a position of rest'during movement of the low-pressure valve is also utilized to move said pilot valve as'soon as the pressure regulator causes a movement of the low pressure valve.

In the accompanying drawings which are illustrative of my invention, Figure 1 shows diagrammatically a mixed pressure turbine and a high pressure reciprocating engine and accumulator; Fig. 2 is a diagrammatic illustration of a governing mechanism; and Fig. 3 is an enlarged sectional view of a low-pressure-valve actuating motor and its pilot valve also illustrating diagrammatically one mode of connecting them to the levers of the governing mechanism.

1 indicates a reciprocating engine of any suitable structure to which steamis supplied from the pipe 2. The exhaust therefrom enters the accumulator 3 from which it passes through a low pressure valveft into the mixed pressure turbine 5. This turbine may be of any suitable type or; construction. The casing of the turbine mounted on a bed-plate 6 and the exhaust from the turbine enters the condenser 7.- High pressure steam is admitted to the turbine by the conduit 8 under the control of the high pressure valve 9.

Referring to Fig. 2, .10 indicates a speed governor that is driven by a shaft 11. The

, latter may be the main shaft of the turbine or a secondary shaft driven thereby; Mounted on the shaft 11 and arranged to be moved by the governor is a sliding collar 12 to which the levers 13 and 15 are pivotally attached. The lever 13 is pivoted at 14. The left-hand end bf the lever 15 is pivotally connected to the piston rod 16 of the motor that actuates the low pressure valve 4. To the lever 15 is also pivotally attached at 17 the stem of the pilot valve 18 which controls the movements of the motor piston 19. The right-hand'end of the governor lever 13 is pivotally attached to a link 20 and the latter is attached to a secondary governor lever 21. This lever is connected to the pilot valve 22 that controls the movements of the motor piston 23, the latter actuating the high pressure valve 9. To the piston rod 24 that actuates the high pressure valve is connected a lever 25 the left-hand end of which is connected to the piston rod 16 that actuates the low pressure valve. Extending between the levers 21 and 25 is a connecting rod 26, the purpose of which will be referred to later. The low pressure pilot valve 18 is located within a sliding sleeve 27, to which fluid under pressure is admitted by suitable means to the space between the piston heads, and the fluid exhausting above and below the piston heads is carried off by suitable conduits. The sleeve is actuated in one direction by a piston 28 and in the opposite direction by a coiled compression spring 29. Fluid is admitted to the under side of the piston by a conduit 30 that is connected to the accumulater 3. The pilot valve 18 and sleeve 27 thus cooperate to form a two part controller, one of said parts being controlled solely by the governor and the other solely by the pressure regulator, the latter modifying the action of the former under conditions of failure of the low pressure source. Owing to this arrangement it follows that the sleeve must share in any movement of the regula tor. For example, if the pressure in the accumulator falls, that is, if the amount of exhaust steam no longer sufiices to maintain the speed of the turbine then the piston 28 will be forced by the spring 29 into a lower position of equilibrium, at the same time moving with it the sleeve 27. Oil or other fluid then has access from the space between the heads of the pilot valve through the' ports to the space above the motor piston 19, thereby causing the latter to move the throttle valve 4: toward its seat. The downward movement of the piston rod 16 is communicated to the governor lever 15 which moves the pilot valve 18 back to its central position thereby closing the entrance and discharge ports of the motor. In other words this part of the mechanism forms a follow-up device. At the same time the piston rod 16 moves downward it.carries with itthe lefthand end of the lever 25 thereby depressing the rod 26 and with it the right-hand end of the secondary governing lever 21. This is made possible by the use of the link 20. As the lever 21 moves downward it carries with it the pilot valve 22 which permits fluid, such as oil, to flow from between its heads through theuncovered port leading to the under side of the motor piston 23. At the same time the fluid from the cylinder space above the piston is permitted to escape. The result of this is to open thehigh pressure valve 9. As the piston rod 24 moves up that the pumping out or discharging of the accumulator is avoided because just as soon as the amount of low pressure steam is insuflicient the low pressure throttle valve in response to the pressure regulator automatically assumes such a position with respect to its seat as will allow the available supply of steam to flow without substantial fall of pressure.

It sometimes happens that steam will enter the accumulator in large quantities causing a sudden rise in pressure in ad- Vance of the low pressure throttle valve, and also in the pressure regulator so that the latter is quickly moved into its final position in accordance with said rise in pressure. The result of this is to fully open the low pressure valve which in turn causes the speed of the machine to increase unt i the governing mechanism can again reduce the passage of steam to the turbine in accordance with the load. This variation of steam pressure always causes over-regulation and hence a variation in the speed of the turbine. To obviate this difiiculty a daslrpot is provided comprising a cylinder 31 and a piston 32, the latter being provided with one or more check valves 33 that open when the piston rises and close auto- .matically, when it moves downward. The

piston is connected to the sleeve 27 by a newer:

lever 34 that is pivoted to a suitable support. By reason of this arrangement sud low pressure steam decreases. In this case a gradual fall of pressure takes place which is not opposed by the dash-pot. As a result no resistance is opposed to the downward movement of the .piston of pressure regulator as the accumulator pressure falls. To state the matter in another way, the dampin device is so arranged that it moves reely in one direction and slowly in the opposite direction.

In accordance with the provisions of the patent statutes,,I have described the princi le of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown isonly illustrative, and that the invention can be carried out by other means. a

' What I claim as new and desire to secure by Letters Patent of the United States is 1. In combination, a mixed pressure turbine, conduits admitting low and high pressure fluid thereto, valve means in the conduits, a governor controlling the action of the valve means, a device moved by the low pressure valve means for causing the high pressure valve means to open whenit closes, and a regulator sensitive to the pressure of the low pressure source of supply for clos-' ing the low pressure valve means independently of the governor.

2. In comblnation, a mixed pressure turbine, conduits admitting low and high pres sure fluid thereto, valves in said conduits, motors for operating the valves, con: trollers for the motors, a speed governor for actuating the controllers, levers connected to the motors and controllers for holding the controller of the high pressure valve in its initial position so long as the low pressure valve follows the movements of the governor, and pressure responsive means acting on one of the controllers to cause its valveto close.

3. In combination, a mixed pressure turbine, conduits admitting low and high pressure fluid thereto, valves in the conduits, a governor, a lever means moved by the governor for controlling both of said valves, a pressure regulator for con clling the low pressure valve independently of the governor, and a second lever means actuated by the low pressure valve that causes-the high pressure valve to open when said low pressure valve closes in response to the action of the regulator.

4. In combination, a' mixed pressure tur bine, conduits admitting low and high pres sure fluid thereto, valves in the conduits, motors for actuating the valves, controllers for the motors, a speed governor that normally actuates both controllers, a means moving with the low pressure valve motor which under certain circumstances moves the controller of the high pressure valve motor, and a regulator responsive to changes in ressure of the low pressure source for modiying the action of the governor on the motor of the low pressure valve.

'5. In combination, a mixed pressure turbine, conduits admitting low and high pres sure fluid thereto, valves in the. conduits, motors for actuating the valves, a controller for the high pressure valve motor, a twopart controller for the low pressurevalve motor, a speed governor, a lever means actuated by the governor and moving one of the controllers, a secondary governing lever actuated by said means for moving the other controller, a lever connected to both motors and to said secondary lever, and a pressure responsive means for actuating one part of the first mentioned cont-roller.

. 6. In combination, a high pressure prime mover, an accumulator receiving the exhaust therefrom, a mixed pressure turbine receiving steam from the accumulator and also high pressure steam, low and high pressure valves, means connecting the valves in such manner that the closing of one causes the opening of the other, a governor means for controlling the valves, and a regulator responsive to pressure variations existing in the accumulator for modifying the action of the governor means on one of the valves.

7 In combination, a mixed pressure turbine, conduitsadmitting low and high pressure fluid thereto, valve means in the conduits, a governor controlling the action of the valve means, a device moved by the low pressure valve means for causing the high pressure valve means to open when said low pressure valve means closes, a regulator sensit-iveto the pressure of the low pressure source of supply for closing the low pressure valve means independently of the governor, and a damping device to prevent sudden increases in pressure in the low pressure source from directly affecting the valve 8. In combination, a mixed pressure turbine, conduits admitting low and high pressure fluid thereto, valves in the conduits, motors for actuating the valves, controllers for the motors, a speed governor that normally actuates both controllers, a means moving with the low pressure "alve motor and which under certain circumstances moves the controller of the high pressure valve motor, a regulator responsive to In Witness whereof, I have hereunto set 1 changesf in pressure of the low pressure my hand this fifth day of December, 1911. source or modifying the action of the governor on the motor of the low pressure valve, VILHELM PAPE' and a damping device that acts on the low Witnesses:

pressure controller and the pressure regu- HENRY HASPER, lator. WOLDEMAR HAUPT.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G."